function draw_line_f1( node1, node2, line_color )

    global S_Map;
    global f1;

    figure(f1);
    X1=[S_Map(node1,1),S_Map(node2,1)];
    Y1=[S_Map(node1,2),S_Map(node2,2)];
    Z1=[S_Map(node1,3),S_Map(node2,3)];
    line(X1,Y1,Z1,'Color',line_color);
    plot3(X1,Y1,Z1,'black.');

end

